Field of the Invention
The invention is directed generally to electronic chip cards and specifically to a method and apparatus for indicating an improper termination of a communication between a chip card and-an associated write/read device.
Description of Prior Art
Modern data communications have been vastly improved, and chip cards are a specific example of such an advance. Chip cards (also referred to as "smart" cards meaning cards carrying a microprocessor and memory and perhaps additional circuitry) provide for data communication between a handheld small card and a write/read head terminal. Many uses exist for these cards,, including automated banking, building access and security, etc. The chip cards are available with or without contacts. During a chip card communication, an interruption or fault can occur if the user improperly operates the device, for example.
A switch is included in the standard equipment of write/read devices for cards having contacts. When the cards are moved out of their final position, the contact terminals of the write/read device contacting the card surface must immediately separate electrically from the card so that no tracks are left on the card contacts, nor is any damage done to the card contacts (see FIG. 1a).
Given cards having contacts, an interruption of the power supply and, thus, an interruption of the faultless functioning of the card occurs immediately with a change of the switch. In practice, this leads to considerable problems since undefined information remains in the memory and makes a later use of the card more difficult and error-prone.
Chip cards that work in a contact-free manner acquire their energy by field transmission with coupling from electromagnetic oscillations. Rectifier circuits at the side of the chip cards are used in the operation of an electronic circuit. As a general rule, capacitors are utilized for charge storage in chip cards that work without contacts.
Write/read devices for cards without contacts also often have a limit switch to indicate a defined inserted position.